Open-cell tungsten nanofoams: Chloride ion induced structure modification and mechanical behavior

In this work, a nanoporous structure composed entirely of tungsten ligaments was synthesized by selective phase dissolution of a nanocrystalline tungsten-copper composite in ferric chloride aqueous solution at room temperature. Observation of the tungsten nanoligament modifications in both ferric chloride and hydrochloric acid solution illustrated that the chloride ions accelerate the surface diffusivity of tungsten atoms by two orders of magnitude, thus causing an evolution of the tungsten nanoligaments upon reconstruction and growth with the increase of dissolution time. Using nanoindentation and Vickers’ microhardness measurements, we discovered that the created tungsten foam deforms via a fast densification in combination with the formation of cracks due to a low ligament strength.